Device for disassembling rolling mill cylinders

ABSTRACT

The invention regards a device for disassembly of the rolls of a rolling mill by translation, successively, on internal ( 5 ) and external ( 55 ) rails whereon run the supporting rollers ( 7 ) of the chocks ( 3 ).  
     According to the invention, each internal rail ( 5 ) is composed of two sections ( 51, 52 ) mounted to slide, respectively, on both standards ( 10, 100 ) of the stand ( 1 ), between a retracted rolling position and a forward disassembly position for which both sections ( 51, 52 ) are brought towards one another, their internal ends ( 53′, 54 ′) being separate by a free space (e), and each chock ( 3 ) is fitted with rollers ( 72, 72 ′) spaced from one another by a distance (d) greater than said free space (e) in order to rest successively on said sections ( 51, 52 ) during the disassembly and the reassembly processes.

[0001] The invention relates to an installation for replacement of the rolls, in particular working rolls, in a roll stand.

[0002] It is known that a rolling mill comprises, inside a stand, at least two rolls mounted to rotate around parallel axes and placed in a plane which is substantially vertical. The <<Duo>> stands, for instance, comprise only two rolls between which runs the product to be rolled. In the so-called <<Quarto>> stands, the product to be rolled runs between two working rolls of relatively small diameter and bearing directly on two back-up rolls. In the so-called <<Sexto>> stands, intermediate rolls are interposed between each working roll and the corresponding back-up roll. But one also knows other types of rolling mills, for example of the <<Sendzimir>> type which comprise a large number of rolls or the so-called <<Z-High>> rolling mills wherein each working roll is associated with lateral back-up rolls, the assembly being placed in an insert.

[0003] The working rolls, which are in contact with the product, wear rather quickly. Besides, their diameter should be suited to the nature and to the thickness of the product to be rolled as well as, in certain cases, to the surface finish to obtain. These rolls must therefore be replaced periodically.

[0004] The same goes for the intermediate rolls in the <<Sexto>> rolling mills, and for the inserts in the <<Z-High>> rolling mills.

[0005] Previously, the rolls were disassembled in a cantilever position by a so-called carrying bar system, comprising a take-up member for the roll balanced by a counterweight.

[0006] However, for several years, devices have been developed with a view to reducing the service time, the risks of damage for people or equipment and enabling automation of the sequences.

[0007] It is known, generally, that each roll is mounted to rotate, at its ends, on centring bearings housed in two chocks whereon bear means for height adjustment of the rolls, each chock being mounted to slide along guiding faces parallel to a clamping plane running through the axes of the working rolls.

[0008] To enable withdrawal and insertion of the rolls, the chocks are fitted, generally, with rollers which run on rails extending between both standards of the stand, parallel to the axes of the rolls.

[0009] In certain cases, to disassemble both rolls together, the upper roll is laid on the chocks of the lower roll which run on two rails placed on either side of the clamping plane.

[0010] However, the continuous rolling technique is used more and more extensively which implies changing the rolls while maintaining the band engaged between both working rolls. In such a case, one uses two pairs of rails for disassembling the rolls placed, respectively, at two levels for which the rolls are away from the band.

[0011] In all cases, the rolls to be disassembled are therefore removed from the stand by displacement parallel to their axis and transferred onto an external device comprising rails placed respectively in the alignment of the rails in the stand and a carriage fitted with motor-driven extracting devices which enable the rolls to come out of the stand or, conversely, insertion of the new rolls.

[0012] To accelerate the process, one often uses two carriages mounted to slide on rails parallel to the running direction and provided on a lateral chassis, one of the carriages comprising an empty recess for receiving the worn rolls and the other carriage carrying new rolls which can be inserted into the stand after extraction of the worn rolls. When disassembly is performed with the band engaged, each carriage comprises two pairs of rails which are placed in the alignment of two pairs of rails of the stand.

[0013] Even if the working rolls have relatively small diameter, their weight is still sizeable and the rails intended for disassembling must therefore have dimensions sufficient to sustain them. These devices are therefore relatively cumbersome and must, however, extend on either side of the clamping plane and in the vicinity thereof since they carry the chocks of each roll to be disassembled.

[0014] Or, generally, the internal zone of the stand, at the level of the working rolls, is already packed with all sorts of devices, such as band engagement tables, spray ramps, devices intended to protect the rolls in case of broken bands, etc. . . . .

[0015] Even in the case of a new stand, it is difficult, in addition to these essential devices, to accommodate rails for disassembly in a confined space. Still, one may use dismountable rails which are placed in the stand only when replacing rolls, but the time necessary to the installation and to the disassembly of the rails increases the whole duration of the process, which defeats the purpose.

[0016] On the other hand, one cannot either reduce the dimensions of the rails without making them dangerously brittle.

[0017] This invention enables to solve these various problems thanks to a replacement device which, without dismounting the rails, enables to clear completely the space between the standards of the stand, during rolling processes.

[0018] The invention therefore generally concerns a device for disassembly of the rolls in a rolling mill wherein the rolls are displaced by translation, parallel to their axis, from a rolling position between the standards of the stand to a disassembly position at a distance from the stand, while bearing, successively, on at least a pair of internal rails extending respectively, on either side of the clamping plane, between the corresponding stanchions of each standard and extended by at least one pair of external rails extending outside the stand, at least on one disassembly side, both chocks of the roll to be disassembled being fitted with bearing members mobile on said internal and external rails.

[0019] According to the invention, on either side of the clamping plane, each internal rail is composed of two sections extending each on a length delineated between two ends, respectively internal and external, and mounted to slide, respectively, on both standards of the stand, parallel to the axis of the roll and the rolling mill comprises means for controlling the sliding motion of both sections of each internal rail from a rolling position for which each section extends substantially on the width of the corresponding standard to a position for disassembly of the roll for which both sections are brought towards one another, in the gap between both standards, the internal ends of said sections being separate by a free space. Moreover, each mobile bearing member of a chock is moved away from the middle plane thereof by a distance greater than the distance between said middle plane and the end of the corresponding rail section when said rail is in the rolling position and at least the chock holding the end of the roll opposite to the disassembly side is fitted, on either side of the clamping plane, with two mobile bearing members spaced from one another, on either side of the middle plane of the chock, by a distance greater than the length of the existing free space, in the position for disassembly of the roll, between the internal opposite ends of both sections of corresponding internal rails.

[0020] According to a preferred embodiment, both chocks of the roll to be disassembled are fitted each, on either side of the clamping plane, with a pair of mobile bearing members spaced from one another by a distance greater than the length of the section of corresponding rail.

[0021] These bearing members composed, preferably, of running rollers, are mounted each at the end of a fixed arm on the corresponding side of the chock and extend axially to the outside of the chock, in order to place the bearing member at the requested distance of the middle plane of the chock.

[0022] On the other hand, it is advantageous that the sections of rails mounted on the same standard of the stand, on either side of the clamping plane, should be connected together and associated with a single means for controlling the simultaneous sliding motion of said sections, from the rolling position to the disassembly position and conversely.

[0023] In case when both working rolls are dismounted simultaneously while laying the upper roll on the lower roll, the device comprises two pairs of sections of rails mounted respectively on both standards of the stand at the same disassembly level, in order to form two internal rails, on either side of the clamping plane.

[0024] According to another more advanced embodiment, enabling disassembly with the band still engaged, the device comprises four pairs of sections of rails mounted respectively, at two disassembly levels, on both standards of the stand, in order to form, at each level, two internal rails extending respectively on either side of the clamping plane. Such a device enables therefore, while keeping the band engaged, to translate, separately or simultaneously, both working rolls while holding them apart on either side of the rolling plane. A similar arrangement enables, in a <<Z-High>> rolling mill, to disassemble and to replace, separately or simultaneously, the inserts comprising each a working roll and two lateral back-up rolls.

[0025] Other arrangements are however possible and one could, for example in a <<Sexto>> rolling mill, use eight pairs of sections of rails mounted respectively at four levels for disassembly of the working rolls and of the intermediate rolls.

[0026] The invention also covers the implementation method of such a disassembly device. According to the invention, once the rolls have been placed at their disassembly level, the sections of rails placed on one front disassembly side are caused to slide towards the inside of the stand, then a replacement carriage fitted with external rails is moved to said side, whereby said rails are placed in the alignment of the sections of internal rails thus fed forward. The translation of the roll to be replaced resting on the sections of internal rails is then controlled and the sections of rails mounted on the rear standard are then fed forward, towards the inside of the stand. The rear chock placed on the side opposite to the carriage rests successively on the rear sections, then on the front sections by its two spaced bearing members, while crossing the free space between said sections. By reverse operations, it is possible to insert into the stand a replacement roll, then to cause the sections of internal rails to slide towards the outside of the stand in order to replace them into rolling position each at the level of a standard, whereby the chocks of the roll can then be moved vertically for adjusting the distance between the working rolls.

[0027] As regards the implementation of the invention, it is particularly advantageous that the rolling mill should be fitted with C-shaped hydraulic blocks comprising, on either side of the rolling plane, two protruding parts at the ends whereof are provided lateral guiding faces of the working chocks, whereby said chocks are fitted with bearing ears offset towards the rolling plane and engaging into a central scalloping of each hydraulic block, provided between the protruding parts thereof.

[0028] Indeed, the sections of rails mounted on each standard can, in such a case, be arranged along the ends of the protruding parts of the hydraulic blocks and each rail is housed in a scalloping provided on a portion of the height of the corresponding lateral side of the chock while keeping, on said lateral side and on the end of the protruding side, guiding faces sliding over one another and having a height compatible with the level adjustment possibilities of the chock.

[0029] Each section of rail is thus mounted to slide axially between the end of the protruding side of the hydraulic block and the bottom of the scalloping provided on the lateral side of the chock, said bottom and the corresponding face of the rail being fitted with wearing plates which slide over one another, on the one hand in the axial direction during displacements of the section of rail and, on the other hand, in the vertical direction when adjusting the level of the chock, in order to form an additional lateral back-up means of the chock.

[0030] The invention also covers other advantageous arrangements mentioned in the claims.

[0031] But the invention will be understood better by the following description of a particular embodiment, given for exemplification purposes and represented on the appended drawings.

[0032]FIG. 1 shows, as an elevation view, the conventional arrangement of a roll stand fitted with various appended members.

[0033]FIG. 2 is a top view of a rolling mill fitted with the device according to the invention, as a sectional view according to the rolling plane P₁.

[0034]FIG. 3 is an elevation view and partially a sectional view along the line III-III of FIG. 2.

[0035]FIG. 4 is a sectional view along the line IV-IV of FIG. 3.

[0036]FIG. 5 shows, diagrammatically, the disassembly sequence of a roll.

[0037]FIG. 1 represents, as an elevation view, the assembly of a conventional quarto-type rolling mill comprising a stand 1, two working rolls, respectively lower 2 and upper 2′, and two back-up rolls 15, 15′. Each roll 2, 2′, 15, 15′ is mounted to rotate, at its ends, on two bearings housed in chocks 3, 3′, 16, 16′ and centred on a middle plane Q orthogonal to the axis of the roll.

[0038] As usual, the holding stand 1 comprises two spaced standards 10 comprising each a window 11 delineated by two stanchions 12 a, 12 b of the standard and wherein are attached the chocks of the rolls which are held laterally by guiding faces 13 sliding parallel to a clamping plane P₂ running substantially through the axes of the rolls, in order to enable height adjustment of the rolls under the control of clamping means 14 bearing on the standards 10 of the stand and of means not represented for adjusting the levels of the rolls.

[0039] As the diameter of the working rolls 2, 2′ is relatively small, the guiding faces 13 of their chocks 3, 3′ are provided on compact parts or <<hydraulic blocks>> 4 which extend and protrude inside the window 11 and carry, in modern stands, hydraulic jacks for cambering the working rolls 2, 2′.

[0040] As shown on FIG. 1, a roll stand is fitted usually with a number of appended members which are situated by both working rolls, close to said rolls, on either side of the running plane of the band to be rolled M.

[0041] For example, such a roll stand may comprise, on either side of the clamping plane P₂, an engagement table A, spray ramps B placed as close as possible to the rolls 2, 2′, a tightening roller C, a bar feeder roller D mounted on a device which enables to bring it closer to or away from the band, as well as guard plates E intended to protect the rolls in case of broken band.

[0042] All these appended members and, in particular, the spray ramps B and the guard plates E must be placed close to the working rolls 2, 2′ in a confined space delineated vertically by the chocks 16, 16′ of the back-up rolls 15, 15′ and laterally by both standards 10, 100 of the stand. It is therefore difficult to place besides, in this gap, rails enabling to dismantle the rolls.

[0043] The invention enables to solve this problem thanks to a unique arrangement of the disassembly rails represented on FIGS. 2, 3 and 4.

[0044] In the embodiment represented on FIG. 1, the chocks of the working rolls are of conventional type comprising two bearing ears placed in the central portion of the chock and whereon act, in opposite directions, cambering jacks, respectively positive and negative, placed on either side of the ear. Each hydraulic block is, therefore, E-shaped comprising a central bearing portion of the positive cambering jacks and two extreme portions, respectively lower and upper, for the negative cambering jacks to bear upon.

[0045] The invention may apply to this type of stand. However, it is particularly advantageous to use the arrangement described in the French patent n°2786415 of the same company, wherein the ears of the chocks are offset towards the rolling plane, whereas each hydraulic block is C-shaped comprising only two protruding portions for guiding the working chocks 3, 3′, wherein are housed the cambering jacks, respectively positive and negative, of the rolls 2, 2′.

[0046] This preferred embodiment has therefore been represented on FIGS. 2, 3 and 4.

[0047] According to the arrangement described in the previous patent n°2786415, the central portion of the hydraulic block is deleted, whereas each positive cambering jack of a chock bears on the protruding side of the hydraulic block placed on the other side of the rolling plane and bound therefore, to run through said plane. To this end, as shown on FIG. 2, the bearing ears of each chock 3 exhibit a staggered profile comprising a protruding portion 31 whereon bear positive and negative cambering jacks of the roll 2 in question and a free space 32 to let through the positive cambering jack of the roll 2′ placed on the other side of the rolling plane. Moreover, the bearing portions 31 a, 31 b placed on either side of the clamping plane P₂ are offset, respectively, ahead of and behind the middle plane Q of the chock, for centring the resultant of the loads applied.

[0048] As divulged in the Patent n°2786415, such an arrangement exhibits notably the advantage of reducing the global height of the hydraulic blocks and of the chocks, since the bearing ears of both chocks can be placed close to the rolling plane, in the central scalloping of each C-shaped hydraulic block.

[0049] In conventional disassembly devices, the running rollers of the chocks are often mounted at the end of the bearing ears and the disassembly rails must therefore be placed between the protruding portions of the hydraulic blocks carrying the cambering jacks. The assembly is rather cumbersome and may hardly be housed between the stanchions of each standard of the stand, in the case, for instance, of modernising an existing rolling mill.

[0050] The arrangement with C-shaped blocks described in the previous patent n°2786415 is, conversely, particularly well suited to the installation of disassembly rails. Indeed, since the bearing ears of each chock are offset on the side of the rolling plane, the whole remaining height of the chock is available to provide the lateral holding faces thereof and it is thus possible to place guiding rails on a portion of the height of the protruding side of the hydraulic block, while preserving the guiding height necessary for adjusting the level of the roll.

[0051] Such an arrangement is represented, in particular, on FIG. 3 which is an elevation view of the hydraulic blocks and of the chocks, partially as a sectional view along the line III-III of FIG. 2.

[0052] As already stated, it is necessary to replace periodically the working rolls because they are worn and this ought therefore to be taken into account in order to determine the height adjustment possibilities of the chocks. FIG. 3 shows, for exemplification purposes, worn rolls on its left-hand side and new rolls on its right-hand side.

[0053] As indicated previously, both working rolls 2, 2′ are carried, at each end, by chocks 3, 30, 3′, 30′, which are mounted to slide vertically between two hydraulic blocks 4 a, 4 b fixed, respectively, on both stanchions 12 a, 12 b of each standard 10, 100 and each hydraulic block 4 comprises two protruding portions, respectively lower 41 and upper 41′, on either side of a central scalloping 42 wherein engage the ears 31, 31′ of both two chocks 3, 3′. In these protruding portions 41, 41′ are housed the cambering jacks, respectively positive 43 and negative 44, of the rolls. Because of the C-shape of the hydraulic block, the positive cambering jack 43 of the lower chock 3 is placed in the upper portion 41′ of the hydraulic block 4 and runs therefore through the rolling plane P₁ to rest on the ear 31 of the lower chock 3 while running through a recess 32 of the upper chock 3′. Because of the offset position, towards the rolling plane P₁, of the ears 31, the lateral guiding faces of the chocks, provided at the ends of the protruding portions 41, 41′, can extend practically over the whole height of the chock. This particular embodiment facilitates the installation of the supporting rails 5, 5′ inside the hydraulic blocks.

[0054] Indeed, as shown on FIG. 3, the supporting rails 5, 5′ can be placed at the level of the protruding portions 41, 41′ for guiding the chocks 3, 3′, as the running rollers 7 are mounted directly on the lateral sides 34 of the chocks and not, as previously, at the ends of the bearing ears.

[0055] If one considers, for instance, the upper chock 3′, it can be seen that, on FIG. 3, because of the relatively great height of the lateral side 34 of the chock 3, it is possible to provide a scalloping 33 wherein may be housed a supporting rail 5′, while preserving sufficient height for guiding the chock, along the remaining portion of the lateral side 34 which is fitted with a wearing plate 35.

[0056] Consequently, the supporting rail 5′, whereof the height h₁ is determined in order to confer it the required resistance, extends along the end 43 of the protruding side 41′ of the hydraulic block 4, while leaving a lateral guiding face 45 of the chock, in contact with the guiding face 35 of the chock and extending on a height h₂ compatible with the necessity to hold the chock laterally along the whole adjustment height of the level, both guiding faces in contact 35, 45 being fitted with wearing plates.

[0057] The lower chock 3 is realised in a similar fashion while taking into account, however, the assembly of the supporting rollers 7 of the chocks which, as usual, must run on the rails 5, 5′ for disassembly of the rolls and are therefore placed above said rolls.

[0058] For example, on FIG. 3 which represents the rolls at their disassembly positions, spaced on either side of the band M to be rolled, it can be seen that the guiding faces 45 of the hydraulic block and 35 of the chock are at the same level and extend over the whole height h₂, whereas the running rollers 7 are situated just above the upper level of the supporting rails 5, 5′.

[0059] Consequently, as regards the upper chock 3′, the rollers 7′ can be placed at the upper portion of the lateral side 34 whereof the lower portion forms the guiding face 35.

[0060] Conversely, as regards the lower chock 3, the running rollers 7 must be placed above the scalloping 33 and the lateral guiding faces 35 are provided at the same level as the chock 3, between the bearing ear 31 and the scalloping 33.

[0061] Besides, according to the invention, each supporting rail 5 is composed of two sections mounted respectively on both standards 10 and 100 of the stand, as represented on FIG. 2. Each roll is therefore associated with two pairs of rail sections placed respectively on each standard 10, 100, on either side of the clamping plane P₂.

[0062] Thus, as shown on FIG. 2, the working lower roll 2 carried, at its ends, by two chocks, respectively front 3 and rear 30, guided respectively in both standards 10, 100 of the stand, is associated with two pairs of rail sections, respectively 51 a, 51 b carried by the front standard 10 and 52 a, 52 b carried by the rear standard 100.

[0063] Since disassembly can take place with the band engaged, the upper roll 2′ is associated, also, with two pairs of rail sections, respectively 51′a, 51′b carried by the front standard 10 and 52′a, 52′b carried by the rear standard 100.

[0064] Moreover, each rail section 51, 51′ is mounted to slide, parallel to the axis of the roll, on a slideway 6, 6′ provided on the corresponding protruding portion 41, 41′ of the hydraulic block 4. Thus, each section of rail may slide axially between a retracted position for which the rail section 51, 52 is brought back to the level of the standard 10, 100 corresponding to the stand and a forward position, represented as a dotted line on the figure, for which both sections 51, 52 of each rail 5 extend towards one another in the gap 17 between both standards 10, 100 of the stand.

[0065] Thanks to this division of each rail 5 into two sections of delineated length, it is possible to place said sections at the level of the protruding portions 41, 41′, between the ends thereof and the lateral sides 34 of the chocks, without disturbing the vertical displacements of the roll.

[0066] Indeed, according to another characteristic of the invention, the supporting rollers 7 of each chock are spaced from the middle plane Q thereof by a distance greater than the distance between said middle plane and the corresponding end of the rail section so that said rail does not risk to interfere with the movements of the roller 7 linked with the chock, during height adjustments thereof.

[0067] This arrangement is represented in detail on FIG. 4 which is a longitudinal sectional view of the rear chocks 30, 30′ placed on the side opposite to the disassembly side of the rolls.

[0068] It can be seen, indeed, that in such a case, each rear chock 30 is supported, on either side of the clamping plane P₂, by two spaced rollers on either side of the middle plane Q of the chock, respectively an external roller 72 placed outside the stand and an internal roller 72′ placed inside, in the gap 17 between both standards 10, 100. Each roller 72 is mounted at the end of an arm 73 fixed on the side of the chock and extending towards the inside or towards the outside so that both rollers 72, 72′ are spaced from one another by a distance d greater than the length l of the section of rail 52. Consequently, the rollers 72, 72′, which are placed beyond the ends, respectively external 54 and internal 54′ of the corresponding rail section 52, do not interfere with the vertical displacements of the chock 3 when the rail section 52 is retracted into rolling position.

[0069] In this view, it should be noted that the vertical displacements of the chocks and the axial displacements of the rail sections never occur simultaneously. Consequently, each rail section 51, 52 may be attached without any clearance between the end face 46 of the protruding side 41, 41′ and the bottom 36 of the scalloping 33 provided on the lateral side 34 of the chock.

[0070] Both faces in contact, 56 of the rail section 51, 52 and 36 of the chock 3, can co-operate with the guiding faces 35, 45 in order to hold the chock laterally and are, to this end, fitted with wearing plates sliding over one another, on the one hand during vertical displacements of the chock and, on the other hand, during axial displacements of the rail section 51, 52.

[0071] Preferably, the front chock 3, 3′ placed at the other end of the roll 2, on the disassembly side attached to the standard 10 of the stand is also fitted, on either side of the clamping plane P₂, with two rollers respectively external 71 and internal 71′ spaced by a distance d greater than the length of the corresponding rail section 52. Thus, both chocks, 3, 30 of each roll 2 are identical. However, the front chock 3 could be supported by a single rear roller 71′, mounted on an arm extending towards the inside of the stand.

[0072] In their disassembly position represented as a dotted line on FIG. 2, the rail sections are brought forward in a cantilever position and must therefore remain embedded on the slideways 6 over a length sufficient to sustain the weight of the roll.

[0073] Moreover, in this disassembly position, the internal opposite ends regard 53′, 54′ of both sections 51, 52 of a same rail mounted respectively on both standards 10, 100 of the stand are separate by a free space of width e.

[0074] The length l of the rail sections and the spacing d between the supporting rollers of the chock must therefore be determined, on the one hand to preserve sufficient embedding length for each section and, on the other hand, so that the spacing of the rollers is greater than the distance e between the ends of two rail sections in order to enable the disassembly of the roll while running successively on both sections, as can be seen later on with reference to the diagram of FIG. 5.

[0075] Obviously, all the arrangements that have just been described for the lower roll 2 while referring to FIG. 2 are identical for the upper roll 2′, said roll being also associated with two pairs of rail sections, respectively 51′a, 52′a and 51′b, 52′b.

[0076] It is advantageous to control simultaneously the sliding motion of the whole rail sections placed on the same standard, between the retracted rolling position and the forward disassembly position.

[0077] In this view, as shown on FIG. 3, on either side of the clamping plane P₂, both rail sections, respectively lower 51 and upper 51′ are connected each by an arm 81, 81′ to a linking plate 8 which extends vertically along the hydraulic block 4 and whereon rests the stem of a jack 82 whereof the body is hinged on the hydraulic block 4, the latter being fitted, in its central portion, with a recess 47 wherein extends horizontally the jack 82.

[0078] As shown on FIG. 4, this linking device 8 is fitted advantageously, in its central portion, with a guiding plate 83 which extends horizontally over the same length as the rail sections 51 and which slide in a horizontal slideway 61, provided on the hydraulic block 4.

[0079] This central slideway 61 co-operates with both guiding slideways 6, 6′ of the rail sections 51, 51′ for holding them in a cantilever forward position for disassembly.

[0080] The operation of the device is represented diagrammatically on FIG. 5 which shows the successive sequences for dismantling the upper roll 2′, whereas these sequences are obviously the same for the lower roll 2.

[0081] On FIG. 5a, both working rolls 2, 2′ are in rolling position of a product M. The spacing of their chocks 3, 3′ depends therefore on the thickness of the product and of the degree of wear of the rolls 2, 2′.

[0082] In this position, the running rollers 71, 72 of the upper chocks 3′a, 3′b can possibly be situated at the level of the upper rail sections 51′, 52′. Indeed, as can be seen, the distance d between the running rollers 71, 72 of each chock 3′a, 3′b is greater than the length l of the corresponding rail section 51′, 52′ and said section counteracts therefore the vertical movements of the chock only under the effect of the adjustment jacks 42, 43.

[0083] When the rolls 2, 2′ are worn and must be replaced, they are spaced on either side of the product to be rolled M, each at its disassembly level, in the position represented on FIG. 5b. The running rollers 71, 72 are then situated just above the level of the upper faces of the rail sections 51, 52.

[0084] The rail sections 51, 51′ mounted on the front standard 10 of the stand placed on the disassembly side are then brought towards the inside of the stand, in their disassembly position. As indicated, the rolling mill is associated, on this side, with an auxiliary carriage carrying external rails 55 which are placed in the alignment of the rail sections 51′, in the position represented on FIG. 5c.

[0085] Preferably, the rail sections 52′ placed on the side opposite to the disassembly side, are slightly retracted in order to be placed beneath the rear rollers 72 of the corresponding chock 30′ of the roll 2′.

[0086] By known means mounted on the auxiliary carriage and not represented on the Figures, one then controls the axial displacement of the roll 2′ carried by its two chocks, the front chock 3′ bearing, by its two rollers 71, 71′ respectively on the external rails 55 and the sections 51′ and the rear chock 30′ running on the rear sections 52′. The latter sections are then brought forward into the position represented on FIG. 5d for which the internal opposite ends 53′, 54′ of the rail sections 51′, 52′ are separate by a space of length e smaller than the distance d between both rollers 72, 72′.

[0087] The rear chock 30′ may therefore cross this space while bearing, first of all, on the rear section 52′ by its rear roller 72, then on the front section 51′ by its front roller 72′.

[0088] Axial displacement of the roll 2′ may then continue as indicated on FIG. 5e until both chocks 3′, 30′ rest on the external rails 55 of the auxiliary carriage.

[0089] Withdrawal of the lower roll 2 unfolds in the same way, whereas each standard is fitted with means for simultaneous control of the forward motion and of the retraction of both pairs of rail sections placed respectively at both disassembly levels.

[0090] In a known fashion, the auxiliary carriage may be fitted with two recesses fitted each with two pairs of external rails 55 placed at both disassembly levels, respectively a free recess for the reception of the worn rolls and a reserve recess comprising two new rolls which are inserted in the stand while following the same sequence in the reverse order.

[0091] But the invention is obviously not limited to the details of the embodiment which has just been described for exemplification purposes, whereas equivalent means can be used without departing from the protection framework defined by the claims.

[0092] In particular, it is particularly advantageous to use chocks fitted with offset ears of the type represented on FIGS. 2 to 4 but the invention would also be applicable to a rolling mill fitted with chocks of conventional type as represented on FIG. 1.

[0093] On the other hand, only the chocks 30, 30′ placed on the side opposite to the disassembly side must cross the space e between both sections of each rail and, consequently, be fitted with two spaced rollers 72, 72′. For simplification purposes, the chocks 3, 3′ placed on the disassembly side could comprise a single roller sufficiently away from the middle plane Q to enable vertical displacement of the chock when the corresponding rail sections are in their rolling position.

[0094] The reference signs inserted after the technical characteristics mentioned in the claims, solely aim at facilitating the understanding thereof and do not limit their extent whatsoever. 

1. A device for disassembling rolls for a rolling mill comprising a holding stand (1) having two spaced standards (10,100) and at least two working rolls, respectively lower (2) and upper (2′), delineating a gap to let through a flat product (M) along a rolling plane (P₁), whereas each roll (2, 2′) is mounted to rotate around its axis on two holding chocks (3, 30, 3′, 30′) centred each on a middle plane (Q) orthogonal to the axis of the roll and attached respectively in two windows (11) provided each between two stanchions (12) of each standard (10, 100), each window (11) being fitted with guiding faces (45) sliding from said chocks parallel to a clamping plane (P₂) running substantially through the axes of the rolls, said rolling mill being fitted with a device for disassembling rolls by translation, successively, on at least one pair of internal rails (5) parallel to the axes of the rolls and extending respectively, on either side of the clamping plane (P₂), between the corresponding stanchions of both standards (10, 100) of the stand (1), and at least one pair of external rails (55) extending from the outside of the stand (1), at least on a disassembly side, each in the alignment of an internal rail (5), both chocks of at least one roll (2) being fitted with bearing members (7) mobile on said internal (5) and external (55) rails, characterised in that, on either side of the clamping plane (P₂), each internal rail (5) is composed of two sections (51, 52) extending each, on a delineated length, between two ends, respectively internal (53′, 54′) and external (53, 54), and mounted to slide, respectively, on both standards (10, 100) of the stand (1), parallel to the axis of the roll, in that the rolling mill comprises means (82) for controlling the sliding motion of both sections (51, 52) of each internal rail (5) from a rolling position for which each section (51, 52) is retracted from the gap (17) between both standards (10, 100) to a position for disassembling the roll (2) for which both sections (51, 52) are brought towards one another, in the gap (17) between both standards (10, 100), the internal ends (53′, 54′) of said sections (51, 52) being separate by a free space (e), in that each mobile bearing member (71) of a chock (3) is spaced away from the middle plane (Q) thereof, by a distance greater than the distance between said middle plane (Q) and the corresponding end of said rail section, when said rail is situated in the rolling position, and in that at least the chock (30) holding the end of the roll (2) opposite to the disassembly side is fitted on either side of the clamping plane (P₂), with two mobile bearing members (72, 72′) spaced from one another by a distance (d) greater than the length (e) of the existing free space, in the position for disassembly of the roll, between the internal opposite ends (53′, 54′) of both two sections (51, 52) of internal rail (5).
 2. A device according to claim 1, characterised in that both chocks (3, 30) of each roll (2) are fitted each, on either side of the clamping plane (P₂), with a pair of mobile bearing members (71, 71′), (72, 72′) spaced from one another, in the axial direction by a distance (d) greater than the length (l) of the corresponding rail section (51, 52).
 3. A device according to either of claims 1 and 2, characterised in that both rail sections (51), (52) mounted on the same standard (10), (100) of the stand, on either side of the clamping plane (P₂), are interconnected with one another by linking means (8) and associated with means (82) for controlling the simultaneous sliding motion of both sections (51), (52), from the rolling position to the disassembly position, and conversely.
 4. A device according to one of the previous claims, for simultaneous disassembly of both working rolls (2, 2′), bearing over one another, characterised in that it comprises two pairs of rail sections (51, 52) mounted respectively on both standards (10, 100) of the stand, at the same level for disassembling a first roll (2) whereon rests the second roll (2′).
 5. A device according to one of the claims 1 to 3, characterised in that it comprises four pairs of rail sections (51, 52), (51′, 52′) mounted respectively, at two disassembly levels, on both standards (10, 100) of the stand (1) for which both rolls (2, 2′) are spaced on either side of the product (M) during a rolling process, in order to form, at each level, a pair of internal rails (5, 5′) extending respectively on either side of the clamping plane (P₁).
 6. A device according to one of the previous claims, characterised in that the mobile bearing members of the chocks (3, 30) are running rollers (71, 72) on the rail sections (51), (52).
 7. A device according to one of the claims 1 to 5, characterised in that the mobile bearing members of the chocks are sliding parts on the rail sections.
 8. A device according to one of the previous claims, characterised in that the rolling mill is fitted with C-shaped hydraulic blocks comprising, on either side of the rolling plane (P₁), two protruding portions (41, 41′) at the ends whereof are provided faces (45) for lateral guiding of the working chocks (3) which are fitted each with two bearing ears (31) for height adjustment of the chock, and in that said bearing ears (31) are offset towards the rolling plane (P₁) and engage into a central scalloping (42) of each hydraulic block (4) provided between the protruding portions (41, 41′) thereof.
 9. A device according to claim 8, characterised in that the rail sections (51, 52) mounted on each standard (10, 100), on either side of the clamping plane P₂), for supporting each roll (2, 2′) are arranged along ends of the protruding portions (41, 41′) of the hydraulic blocks (4) and are housed in scallopings (33) provided on a portion of the height on either lateral side (34) of a chock (4), while keeping on said lateral side (34) and on the end of the protruding side (41, 41′) guiding faces (35, 45) sliding over one another and having a height (h₂) compatible with the level adjustment possibilities of the chock (3).
 10. A device according to claim 9, characterised in that each rail section (51, 52) is mounted to slide axially from the end of the protruding side (41, 41′) of the hydraulic block (4) to the bottom (36) of the scalloping (33) provided on the lateral side (34) of the chock (3), said bottom (36) and the corresponding face (46) of the rail (51, 52) being fitted with wearing plates sliding over one another, on the one hand in the axial direction during the displacements of the rail section (51, 52) and, on the other hand, in the vertical direction during level adjustments of the chock, in order to form additional means for lateral holding of the chock (3).
 11. A device according to one of the previous claims, characterised in that each mobile bearing member (71, 72) of a chock (3, 30) is mounted at the end of an arm (73) fixed on the chock and extending axially over a length such that said bearing member (71, 72) is spaced away from the middle plane Q of the chock (3) by a distance greater than the distance between said middle plane (Q) and the corresponding end (53, 54) of the rail section (51, 52).
 12. A device according to either of claims 10 and 11, characterised in that each rail section is mounted to slide axially on a slideway (6) provided on the end of the protruding side (41, 41′) of the hydraulic block and in that, in the forward disassembly position, the slideway (6) associated with each rail section (51, 52) remains engaged in said protruding portion (41, 41′) over an embedding length sufficient for holding in a cantilever position the rail section (51, 52) under the load of the roll (2).
 13. A device according to claim 12, comprising, on each standard (10, 100) of the stand (1), two pairs of rail sections (51, 51′), (52, 52′) placed at two disassembly levels, respectively, of both working rolls (2, 2′), characterised in that both rail sections (51, 51′) (52, 52′) placed on each standard (10, 100) and on each side of the clamping plane (P₂) are interconnected by a linking member (8) whereon rests a first element of a jack (82) controlling the axial displacement whereof the second element rests on the standard (10, 100) and in that both jacks (82) placed respectively on either side of the clamping plane (P₂) are actuated in a synchronous fashion for the control of simultaneous axial displacement of the rail sections of both pairs (51, 51′) (52, 52′).
 14. A roll replacement process in a rolling mill fitted with a device according to one of the previous claims, associated with a replacement carriage placed on a side for disassembly of the stand, wherein each rail (5) for disassembly of a roll is composed of two sections (51, 52) mounted to slide parallel to the axis of the roll (2, 2′) each on a standard (10, 100) of the stand, characterised in that, after having placed each roll (2, 2′) at its disassembly level, internal rail sections (51) mounted on the front standard (10) placed on the disassembly side are caused to slide towards the inside of the stand, the replacement carriage which is fitted with external rails (55) situated in the alignment of the sections (51) thus brought forward, are fed towards this standard (10), then the translation of the roll to be replaced (2, 2′) is initiated, which rests on both pairs of rail sections (51, 52), then the sections (52) placed on the rear standard (100) are fed forward and the roll is fed forward further, whereof the rear chock (30) rests successively on the rear (52) and then on the front (51) sections by its two spaced bearing members, while crossing the free space between said sections, until the worn roll rests on the replacement carriage and, by reverse operations, one inserts into the stand a new roll, then the rail sections (51, 52) are caused to slide towards the outside of the stand in order to put them back into rolling position, each being taken up in a standard (10, 100). 